(1) Filed of the Invention
This invention relates to methods of forming a laminated yoke for the write head portion of a high data-rate giant magneto-resistive read-write transducer head.
(2) Description of the Related Art
Giant Magneto-Resistive read-write transducer heads having stitched pole magnetic write heads have data rates in the range of 500 Megabytes per second, however there is a strong need to increase the data rates of these transducer heads. Data rates of 700 Megabytes per second or even higher are desirable. To achieve these higher data rates it is necessary to use a laminated yoke design in the magnetic write head portion of the read-write transducer heads.
U.S. Pat. No. 5,283,942 to Chen et al. describes a method of fabricating a narrow thin film head. The method uses a sacrificial layer to provide control of the gap planarization procedure.
U.S. Pat. No. 5,856,898 to Ohashi describes spiral wiring patterns to provide current coils in a magnetic write head.
U.S. Pat. No. 5,805,392 to Mallary et al. describes methods of forming laminated pole pieces for magnetic write heads. Thin film layers of a magnetic material are used to form a pole piece of a thin film head.
U.S. Pat. No. 5,843,521 to Ju et al. describes a method for forming a magnetic transducer head using a photoresist frame plated pole layer. The method is used to achieve a desired shape of the frame plated pole layer.
To achieve high data rates, in the range of 700 Megabytes per second or higher, it is very desirable if not necessary to use a laminated yoke design in the magnetic write head portion of read-write transducer heads. In addition to laminating the yoke it is necessary to properly shape the yoke and pole tip regions of the magnetic write head. With a conventional pole and yoke laminated structure dry etching is the preferred solution to define the pattern of the pole and yoke. The poles fabricated by this technique, however, are limited by the ability of the dry etching technique to produce small dimension pole geometry.
It is a primary objective of this invention to provide a method of using a patterned dielectric process with a form plated pole and yoke process to form a pole and laminated yoke for a high data rate magnetic transducer head.
This objective is achieved by depositing a full film layer of first ferromagnetic material on a base. A patterned layer of first non-magnetic dielectric is then formed on the full film layer of first ferromagnetic material. The patterned layer of first non-magnetic dielectric is patterned using wet etching techniques or lift-off techniques. A layer of photoresist is then formed on the full film layer of first ferromagnetic material and the patterned layer of first non-magnetic dielectric. The layer of photoresist is then patterned to define the yoke dimensions and shape. The patterned layer of photoresist is then used as the frame for frame plating a patterned layer of second ferromagnetic material to form the upper yoke piece.
The patterned layer of second ferromagnetic material forming the upper yoke piece has a thickness of about four to ten times that of the thickness of the full film layer of first ferromagnetic material and is used as a hard mask to define the shape of the full film layer of first ferromagnetic material. The full film layer of first ferromagnetic material is then patterned using the patterned layer of second ferromagnetic material as a mask and ion beam etching, thereby completing the laminated yoke.
The base typically is a first ferromagnetic shield formed on a substrate. A layer of second non-magnetic dielectric is formed on the first ferromagnetic shield and a second ferromagnetic shield is formed on the layer of second non-magnetic dielectric. The second ferromagnetic shield also serves as a pole piece for the magnetic write head. A magnetic sensing element is located in the layer of second non-magnetic dielectric and between the first ferromagnetic shield and the second ferromagnetic shield. A layer of third non-magnetic dielectric is formed on the second ferromagnetic shield to form the magnetic gap between the pole pieces of the write head. A ferromagnetic pole piece, a ferromagnetic back gap piece, and one or more layers of wiring are then formed on the layer of third non-magnetic dielectric to complete the base.